> even this one is way overkill for what I want in a phone. Why can’t there just be a low-spec one instead
Exactly this.
My solution is: dirt-cheap bargain-basement Chinese phones.
They do the job and you can get a lot for under £150.
My best buy was an Umidigi F2. Stunning device for £125. I have bought dinners that cost more than that.
*But* you'll never get an OS upgrade, they're unsupported by all the alternative OSes, and there is the everpresent risk of spyware.
For me, that's worth it, but I get that it's not for everyone and so I do not unequivocally recommend them.